Crystallinity-Governed Liquid Wettability and Mobility on Solid Surface

Control over liquid wettability and droplet mobility is essential for several emerging applications including open microfluidics, anti-icing, self-cleaning, and heat transfer. Existing strategies generally rely on permanent chemical modification or continuous external stimuli to regulate droplet spreading, pinning, and sliding. Here, we report a unified approach for reconfiguring wettability states and droplet mobility by regulating crystalline packing of a semicrystalline polymer. A phase-transitioning polymer, poly(octadecyl acrylate) (PODAc), was incorporated into a porous polymeric coating, where melting and subsequent cooling pathways determine the extent of alkyl-chain crystallization and interfacial polar functionality. Cooling in air or underwater generates reversibly switchable hydrophilic (θ_W ∼ 85°), hydrophobic (θ_W ∼ 104°), and amphiphobic slippery states across liquids with surface tensions of 22-72 mN m^-1. These distinct regimes enable programmable droplet spreading, pinning, and low-friction transport without post-synthetic chemical treatment or sustained external stimulation. Furthermore, reconfigurable wettability patterns enable guided liquid transport through spatially selective complete wetting or customized contact line frictional force.